OPTICAL RECORDING MEDIUM, REPRODUCTION APPARATUS OF OPTICAL DISK, REPRODUCTION METHOD OF OPTICAL DISK, PRODUCTION METHOD OF ORIGINA L DISK OF OPTICAL DISK, AND ILLEGAL PROGRAM OPERATION STOP METHOD

摘要

This invention provides a copy-protected optical disk (9), a reproduction apparatus (47) of the optical disk, a reproduction method of the optical disk, a production method of an original disk of the optical disk and a method of preventing an illegal program operation. An area in which a CP signal (24) having the center of an eye pattern deviated from the center of an amplitude is recorded is disposed at the back of a predetermined pattern signal in the optical disk. A reproduction apparatus additionally has the function of detecting an arrangement information (25) of the CP signal or a CP preceding signal (26), applying an offset voltage to a threshold value at the time of demodulation of an RF signal to a digital signal to change the threshold value, normally reproducing the signal having the center of the eye pattern deviated from the center of the amplitude, and stopping reproduction when a predetermined offset signal is not reproduced.